402 PROCEEDINGS OP SECTION C. 



II. (c) TRAVERSE ALONG BEE (6) REEF. 



In this reef the horseshoe shape does not obtain, but the " mor- 

 phological axis " still runs north-west and south-east (see Plate II.). 

 It is an elongated oval, somewhat over one mile long. The windward 

 (south) end is surmounted by an immense " clinker embankment " 

 rising several feet above high-water mark. The northern end consists 

 of pure sand without live coral, but composed very largely of the tests 

 of foraminifera and coral remains. It is half a mile wide. 



The reef is extending rapidly to the north, being " pushed " along 

 by the strong tidal currents sweeping along each side, which also tend 

 to drop sediment at the jumble of cross currents just to leeward of the 

 island. 



RESUME OF ZONES COMMENCING AT NORTH _^ 

 (Vide Plate I., Fig 3). 



1. Mound of pure sand, due largely to tidal action 400yds. 



2. Shallow sandy " col " joining 1 to 3 300yds. 



3. Flat sandy area, with coral fragments and coral slabs 500yds. 



4. Shallow pools becoming more rocky towards south ; 



Tubipora plentiful 200yds. 



5. Long tongue from " clinker " bank, 15ft. wide, rising 



to 4ft. high 300yds. 



6. " Clinker " bank, 12ft. high at the front south face 



and 40ft. wide 12ft. 



7. Bare coral rock pools, &c., to growing coral zone. . . . 200yds. 



The area to the south of this striking " clinker rampart," which 

 had an abrupt windward face but was " stepped " on the lee side, had 

 been swept clear of living coral apparently by the northward move- 

 ment of the clinker over it. To the lee of the latter the growing Tubi- 

 pora was being rapidly demolished by the long tongue of clinker sent 

 out from the eastern end of the clinker bank. The " flow structure " 

 of the " tongue " was very noticeable. Each succeeding layer terminated 

 in a well-defined " step," such as lava flows of a viscous nature show 

 at their limit of advance. The " step " and the angle of repose (6°) 

 are indicated in the third figure on Plate I. 



III. THE NEGROHEADS. 



Sailing past almost any reef on the Barrier the traveller's atten- 

 tion is arrested by a row of crags, like huge milestones, irregu- 

 larly disposed along the crest of the reef. Even when the bank is 

 covered with high water they project above the surface of the sea. 

 To these Flinders applied the name of " negroheads," converted in 

 local parlance to " niggerheads." If the negroheads gathered on a 

 steep and narrow shore they would compose a " hurricane beach." 



The following description is based on those observed on Cairns 

 Reef. At a distance of a mile or so, by optical illusion, perhaps partly 

 mirage, partly lack of standards of comparison, the negroheads are 



